A Generally Regarded As Safe for humans (GRAS) microorganism is a Food and Drug Administration (FDA) designation for a microorganism regarded as safe for consumption. Lactobacilli are Gram positive bacteria that are currently used in food fermentation and preservation. Lactobacilli are also normal constituents of human microbiota and are classified as GRAS organisms. Lactobacilli are useful system for delivery of therapeutic and prophylactic bio-molecules.
Some infectious diseases are transmitted through the passage of mucosal layer into the cell environment in which the infectious agent multiplies. Blocking the passage through the mucosal layer can be an effective measure against an infection.
A therapeutic product combined with a vehicle capable of safe and long-term delivery of the therapeutic product is useful: it reduces hospital visits, economic cost of administration and can provide prevention of a disease. For example, a drug-containing stent has been used for long-term release of a drug at the site of implantation.
In addition to delivery capability, a vehicle that can produce therapeutics is useful for continuous delivery of the therapeutics. A genetically modified microorganism is suitable to produce biological therapeutics, such as nucleic acids or proteins, and can deliver the biological therapeutics continuously.